Stoker apparatus



oct' 6 1953 D. .LMOSSHART 2,654,331

sToKER APPARATUS Filed May 26. 195o l Il WITNEssEs: n glffgf v w NMA INVENTOR Donald J. Mosshclr ATTORNEY Patented Oct. 6, 1953 STOKER APPARATUS Donald J. Mosshart, Ardmore, Pa., assignor, by mesne assignments, to Detroit Stoker Company, a corporation of Michigan Application May 26, 1950, Serial No. 164,347

3 Claims.

Yet another object of the invention is to pro-1 vide novel mechanism for supplying fuel from a pair of spreader-type stokers to a rectangular grate surface in such a manner that substantially the entire area of the grate is uniformly supplied with fuel.

Another object of the invention is to provide novel means for varying the trajectories of fuel blown into a furnace, together with means for preventing furnace pulsations normally resulting therefrom.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a horizontal sectional View of a furnace equipped with the novel arrangement of fuel spreading mechanism constituting the subject matter of the present invention;

Fig. 2 is a vertical sectional View taken along the line II-II of Fig. 1, looking in the direction indicated by the arrows;

Fig. 3 is an enlarged fragmentary view of the nozzle structure shown in Fig. 2;

Fig. 4 is a fragmentary elevational View of the discharge end of the nozzle structure of Fig. 3, and,

Fig. 5 is a vertical sectional view through `one of the fuel feeders of Fig. 1.

Referring now to the drawings in greater detail, the reference character lll indicates, in its entirety, a furnace comprising front and rear walls II and I2, respectively, and opposed side walls I3 and I4 cooperating with the front and rear walls II and I2 to define a combustion chamber I5.

Conventional grate structure I6 extends between the four walls and defines a bottom for the combustion chamber I5.

Coal is fed to the fuel supporting surface of the grate in the usual manner from hoppers I1 by spreader type fuel feeders I8, the fuel being projected through openings I9 in the furnace front wall onto the fuel-supporting surface of the grate I6.

The fuel feeders I8 may be of any conventional form, for example, of the forms shown in applicants ypreviously issued Patents Nos. 2,386,336 and 2,387,600. As herein illustrated, the feeders I8 may include a ram 3 for pushing fuel, fed from hopper I1, to the rear discharge edge of a spill plate 4 for gravity feed to the blades of a rotary impeller 5 which projects the fuel rearwardly `through the opening I9 in the furnace front wall II to the grates I6.

In many installations wood is available to supplement the coal as a fuel supply and, in order to effectively feed such wood fuel to the grate surface, the furnace may be provided with a pair of nozzles, indicated in their entirety by the reference character 20. In accordance with the present invention, one nozzle 20 is associated with the side wall I3 near the rear wall I2 and another nozzle 20 is associated with the opposite side wall I4 but near the front wall II with the two nozzlesin substantially diametrically opposed relation.

Each nozzle 20 is mounted for limited oscillatory motion about a vertical axis and extends through an opening 2l in the furnace side wall with whichit is associated, the opening being of sufficient lateral extent to provide for the limited oscillatory motion desired.

Referring now to Fig. 3, each nozzle 20 includes a lower flanged inlet 22 for admission of air to the nozzle and a corresponding flanged upper inlet 23 for admission of fuel to the nozzle. The flanged inlet 22 is rotatably mounted in a mating air supply inlet fitting 24 which is supported in fixed position by bracket 25 to a plate 21 mounted on the outer surface of the furnace side wall I3. Similarly, the fianged fuel inlet 23 is rotatably mounted in a mating fuel supply fitting 28 which is secured by bracket 29 to the plate 21 which carries the lower air supply fitting 24. The fuel supply fitting 2B is secured to the lower end of a fuel supply conduit 3| which functions in a manner to be described later.

The nozzle 20 includes a main oscillatory casing 32 provided with an air passage which leads from the inlet fitting 22 tov a Venturi passage 33, the latterv discharging into a mixing chamber 34 from which combined air and wood particles are discharged through an exhaust nozzle 36 to the combustion chamber I5 of the furnace. The main nozzle body 32 may be provided with a bracket 31 or similar means to which suitable mechanism, such as a servo-motor 31a may be connected for imparting the desired oscillatory motion to the nozzle 20.

Wood particles may be supplied from any suitable storage device (not shown) to a vertical conduit 38 from which they are deposited upon the upper run of an endless belt 39 conveying them horizontally any required distance to the upper or inlet end of the vertically disposed supply conduit 3l which communicates, .as previously indicated, with the mixing chamber 34 and the nozzle 20.

It will be apparent that when Wood and air are supplied tofthenozzle 201the. airborne wood particles` will be: projected intoi the combustion chamber and, as the nozzle is oscillated, the trafront Wall for feeding fuel to the grate structure through corresponding openings in said front Wall; a nozzle associated with each of said side walls, one of said nozzles being near the front wall and the other nozzle being near the rear Wall; means mounting said nozzles for limited oscillatory movement about substantially vertical aXes; means for: feeding airborne fuel through said" nozzles to the grate structure; and

jectories of the wood particles will be swept. l0, means fOI imparting OSCillatOIy motion to Said through an arc which arc will be between limits which at one side will be either the front orf rear wall of the furnace and at the other side/will be.. a diagonal connecting tha two. nozzlesl asv cated by the dot-and-dash line X in Fig'. I.. As indicated in the latter figure, this arrangement provides for supply of wood particles tm substantially the entire area of the grate sur face.

In installationswhere the width ofthe furnace fairl'y long, it willA doubtless bei desirabfe to provide means for varying the trajectoriesL of the Wood' particles' to vary the distances they travel and hence the points at which they fall to the grate surface. In any/event; the nozzles should be located a substantial` distance above the grate. surface in order' that' the fuel` particles K will not fall' upon. the grate` untilV they'havetravel'ed the desired'. distance transversely of the grate. Also, with. relatively Wide grates; means should' beY provided for varying' the air pressure in order to vary'the trajectory'of the fuel; and tothe end, there is shown. schematicallyat' il in Fig. 3', adevice which; when constantly rotated, will continuallyvary the' amount of' airl admitted to the nozzle and' hence will conti'nuall'yv vary the trajectories ofthe airborne fuel' particles:

In order. to prevent furnace pulsations result- Ving from variations in the air pressure supplied to the nozzle, the installation should; include suitable mechanism (not shown obvious to one skilled' in the art)- fr increasing" thev air pressure' supplied' to one` nozzle while' decreasing' the pressure of air supplied: to'the' other nozzleL so that the totalpressureand" quantity' of air supplied'. to the furnace will= remain' substantially constant` for any given set' of' operating' conditions;

Whilel the drawings and above descriptionA relate tov a preferred embocli'mentI of the: inven -4 tion wherein the nozzlesA are utilized for supplying wood' as' a supplementale fueii, it' wiliI be apparent: to4 those skilled in the'- art tliatf the nozzles may-be used for Woodx a-lone'- or'f'er any' other fuel alone; or' in combina-tion with coal.l Consequently, while the-invention hasbeen show-n1 in but one form, it will be; obvious toI those skilled in the art' that it is not scfl limited, but is'- susceptible ofv various' changes and' modifications without departing' from the spirit thereof?.l

What is claimed ist' 1. In a furnace', front', rear and side walls deliningv a combustion chamber;y grate` structure forming a bottom for said chamber; one or more spreader-type stokers associated. with said.

nozzles to feed the airborne fuel to the grate over two segments of circles covering substantially the entire grate surface.

2". In aTv furnace; first and second opposed side Walls; third? and; fourth opposed side walls joiningthe firsta-ndsecond Walls and defining there- Witlna combustion chamber rectangular in horizontal cross section; rectangular grate structure forming a bottom for said chamber; one or more fuel-feeding devices associated with the first side. Wall. for feeding; fuel; to' the grate; a nozzles associated. with. eachv of; said, third. and fourthsidef walls', one of said: nozzles; being; near the rst sidel wall and: the other.J nozzle. being near the second side Wallv whereby they are located. substantially4 diagonally opposite; each other; means; for' feeding airborne: fuel particles througl'i; said nozzles to the; grate; and means mounting saidf nozzles'.Y for. oscillatory movement about substantially' vertical axesY between limi-ts such that one nozzle feeds fuel particles: toi approX-imately oneY half the? total.Y area of thegrate and the' other. nozzle'4 feedsA fuel. particles to: approxim'ately` the other. halfr of the totali area of the: grate;4 said halves lying substantially at. opposite sides of a line Iioining the diagonally-disposed nozzles.

3;. In aturnace;` four. walls dening arectangula): combustion chamber; gratev structure.- forming a bottom for the combustione chamber.; a. nozzle associated With each Wall. of anopposed of the: four Walls, each; of said nozzles being; disposedV near. an; endg of itsl wallan the two nozzles beingl near d-ia-metrically-opposed corners of the rectangular combustion. chamber; means mountingY saidl nozzles. for limited oscillatory movement about. substantially` verticalV axes; means for feeding fuel through. said nozzles. to thegrate structure;A and means for imparting oscillatory motion. to said', nozzlesf to. feed the fuel. te the gra-te; over two.- segnients. of circles covering' substantially the entire,Y grate. surface.

DONALD J. MOSSHART..

References Cited in the le, of this. patent UNLITEDf STATES. PATENTS Number Name Date'-v 789g'796" Cooke May' IG, 1905 1,264,369- Cooper Apr. 301, 1918 Z-,3229 Sammons Sept. 13', 1938 FOREIGN PATENTS Numberl Country Date 6471417 Germany July 3.-,. 1937 

